a trick i discovered is that you can use target arcs to read the terrain. Target arc are rendere above the terrain, but they follow it in elevation. Due to their transparent visualisation, if you lower the camera, your target arc will clip into itself and overlap on reverse slope positions. this way you can really read the blindspots of any given position fairly well. the screenshot is from a shock force 2 scenario. all the less transparent areas show potential ditches that offer valuable cover.
one thing i have noticed about buildings that is very annoying is that LOS seems to be calculated from the top edge of the floor, rather than a midpoint of the wall, or the position of the windows. this is especially annoying when you encounter enemies in reverse slope buildings.
in the screenshot all the windows are visible. but due to engine limitations the floor of the building is forced to level the terrain, thus creating a very short reverse slope denying all area fire.